﻿<p>The <em>IfcElementAssembly</em> represents complex element assemblies aggregated from several
elements, such as discrete elements, building elements, or other elements.</p>

<blockquote class="example">EXAMPLE Steel construction assemblies, such as trusses and different kinds of frames, can be represented by the
<em>IfcElementAssembly</em> entity. Other examples include slab fields aggregated from a number of precast concrete slabs or
reinforcement units made from several reinforcement bars. Also bathroom units, staircase sections and other premanufactured or
precast elements are examples of the general <em>IfcElementAssembly</em> entity</blockquote>

<blockquote class="note">NOTE&nbsp; The <em>IfcElementAssembly</em> is a general purpose entity that is required to be decomposed. Also
other subtypes of IfcElement can be decomposed, with some dedicated entities such as <em>IfcWallElementedCase</em> and
<em>IfcSlabElementedCase</em>.</blockquote>

<p>The assembly structure can be nested, i.e. an <em>IfcElementAssembly</em> could be an aggregated part within another <em>IfcElementAssembly</em>.</p>
<blockquote class="note">NOTE&nbsp; View definitions and/or implementer agreements may restrict the number of allowed levels of
nesting.</blockquote>

<p>The geometry of an <em>IfcElementAssembly</em> is generally
formed from its components, in which case it does not need to
have an explicit geometric representation. In some cases it may
be useful to also expose an own explicit representation of the 
aggregate.</p>

<blockquote class="note">NOTE&nbsp; View definitions or implementer
agreements may further constrain the applicability of certain
shape representations at the <em>IfcElementAssembly</em> in respect
of the shape representations of its parts.</blockquote>



<blockquote class="history">HISTORY&nbsp; New entity in IFC2x2.</blockquote>

<p class="spec-head">Informal Propositions:</p>

<ol>
 
<li>The <em>IfcElementAssembly</em> shall have an aggregation
relationship to the contained parts, i.e. the (INV)
<em>IsDecomposedBy</em> relationship shall be utilzed.</li>

</ol>

